Help me fix my bouncy ride.

Does anyone else think their lowered pp GT ride rough? When I got the car it was lowered on Eibach Prokit springs and it seemed a little harsh and bouncy. So I proceeded to swap the springs with some Sportlines. Of course the ride got a little more harsh and bouncy.

I’m hoping by upgrading shocks and struts I can tame it a bit. My question is which shocks and struts would y’all recommend to mate up with my Sportlines and why? Thanks for the help.

Two things: 1) are your bumpstops trimmed? They need to be. 2) PP shocks and struts are fine for the Pro kit springs, but not quite enough for the sportlines. Going to sportlines definitely was the wrong way for bounce. If you are intent on keeping those springs, you're much better off with an upgraded damper (Koni, Steeda, Bilstein). If you go back to Pro Kit or BMR performance or Steeda Ultralite, you can run the PP shocks and struts. I would recommend using the billet shock mounts from steeda regardless of which path you take. They greatly reduce/eliminate bounciness because of the spherical bearing in the mount.

BmacIL said:

Two things: 1) are your bumpstops trimmed? They need to be. 2) PP shocks and struts are fine for the Pro kit springs, but not quite enough for the sportlines. Going to sportlines definitely was the wrong way for bounce. If you are intent on keeping those springs, you're much better off with an upgraded damper (Koni, Steeda, Bilstein). If you go back to Pro Kit or BMR performance or Steeda Ultralite, you can run the PP shocks and struts. I would recommend using the billet shock mounts from steeda regardless of which path you take. They greatly reduce/eliminate bounciness because of the spherical bearing in the mount.

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Thanks for the reply. I didn’t trim the bump stops, but I did use the one supplied with the spring kit. Can you post a link to a how to on trimming the bump stops? Are you supposed to trim the Eibach or factory bump stops? Thanks

S550MG said:

Thanks for the reply. I didn’t trim the bump stops, but I did use the one supplied with the spring kit. Can you post a link to a how to on trimming the bump stops? Are you supposed to trim the Eibach or factory bump stops? Thanks

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Eibach factors in the bumpstops into their effective rates, but I am not a fan of that as it's pretty non linear. I would definitely trim your stock ones and use those. Trim per Steeda's instructions for their ultralite linear springs.

BmacIL said:

Eibach factors in the bumpstops into their effective rates, but I am not a fan of that as it's pretty non linear. I would definitely trim your stock ones and use those. Trim per Steeda's instructions for their ultralite linear springs.

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Unfortunately I don’t have the factory bump stops. The car had the pro kit springs on it when I bought it and already had the Eibach bump stops on it. Maybe a set of factory bump stops wouldn’t be too expensive from a dealer. Or maybe I could just trim the Eibach bump stops.

S550MG said:

Unfortunately I don’t have the factory bump stops. The car had the pro kit springs on it when I bought it and already had the Eibach bump stops on it. Maybe a set of factory bump stops wouldn’t be too expensive from a dealer. Or maybe I could just trim the Eibach bump stops.

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They're pretty inexpensive. The only issue with trimming the eibach ones is that they're definitely softer, so trimmed they may not protect the damper with a big impact.

Another option is Steeda's adjustable bump stops ($48 this weekend)

I can confirm the Steeda billet shock mounts were a huge improvement in the bounciness. I just did it this weekend and what a difference.

So I did a Black Friday thing. I took advantage and ordered quite a few things from the Steeda website. Adjustable shocks and struts, camber plates, rear shock mounts, adjustable bump stops, and an irs bushing kit to help with wheel hop, even though I don’t ever really launch it hard.

S550MG said:

So I did a Black Friday thing. I took advantage and ordered quite a few things from the Steeda website. Adjustable shocks and struts, camber plates, rear shock mounts, adjustable bump stops, and an irs bushing kit to help with wheel hop, even though I don’t ever really launch it hard.

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Congrats!
Please post an update after everything is installed

sublimaze said:

Congrats!
Please post an update after everything is installed

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Thanks, I will for sure. I guess I'll start a build thread as well to help document the build. I'm also getting some wheels and tires. This should complete stage one of my "handling upgrades". Stage two next.

V8EATR said:

I can confirm the Steeda billet shock mounts were a huge improvement in the bounciness. I just did it this weekend and what a difference.

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Yep. People doubt it, but they are a big change.

OP, congrats on the upgrades. You'll have a much improved ride and handling.

BmacIL said:

Two things: 1) are your bumpstops trimmed? They need to be. 2) PP shocks and struts are fine for the Pro kit springs, but not quite enough for the sportlines. Going to sportlines definitely was the wrong way for bounce. If you are intent on keeping those springs, you're much better off with an upgraded damper (Koni, Steeda, Bilstein). If you go back to Pro Kit or BMR performance or Steeda Ultralite, you can run the PP shocks and struts. I would recommend using the billet shock mounts from steeda regardless of which path you take. They greatly reduce/eliminate bounciness because of the spherical bearing in the mount.

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^This...

Also, I installed and therefore been in a car with the Prokit springs and PP dampers --- wasn't bouncy. He used the Steeda adjustable bump stops. The supplied Eibach bump stops are the same size as his stock ones. Maybe a softer durometer I guess? I don't know. But we put his Eibach bump stops up against the stock ones because he was considering just returning the Steeda bump stops and they looked the same height, just didn't have the metal band thing, so I used the Steeda bump stops and just used the one half, not the full height. Prokits were a little stiff feeling, though - for what rate they are... that surprised me.

BmacIL said:

Yep. People doubt it, but they are a big change.

OP, congrats on the upgrades. You'll have a much improved ride and handling.

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V8EATR said:

I can confirm the Steeda billet shock mounts were a huge improvement in the bounciness. I just did it this weekend and what a difference.

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Hope you 2 are right 'cause I also ordered a set from Steeda.com.

Mustang_Lou said:

Hope you 2 are right 'cause I also ordered a set from Steeda.com.

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Ditto. I’m itchy to see the results.

OP, great upgrade choices. A tip: when aligning your car, let the shop know that the rear wheels can adjust camber with motivation. This way, you can dial-in good numbers for both front (with your camber plates) and back.